Compression refrigeration working fluid



' plating.

Unite States Patent 2,975,137 COMPRESSION REFRIGERATION 'WORKING FLUIDArchibald P. Stuart, Media, Pa., assignor to Sun Oil Company,Philadelphia, Pa., a corporation of New Jersey No Drawing. Filed Dec.30, 1955, Ser. No. 556,448

10 Claims. (Cl.'25268) This invention relates to an improved compressionrefrigeration working fluid comprising a halogen-sub stitutedhydrocarbon refrigerant, a mineral oil lubricant, and a copper platinginhibiting amount of :a group lV-B organo-metallic compound.

In compression refrigeration systems Which employ a halogen-substitutedhydrocarbon refrigerant and a mineral oil lubricant, copper plating isan important problem. Copper is removed from parts of the refrigerationapparatus which are formed of this metal, ;e.g., heat exchanger tubes,and the removed copper is transported to non-copper parts of the system,especially ferrous parts, where it is deposited as a layer or plate.Moving parts of the system which continually require lubrication such ascompressor parts are particularly.susceptible to. copper The copperplating increases wear .of moving parts and causes operationaldiflicu'lties and even failure of refrigeration systems.

Now in accordance with the present invention,"there is incorporated inthe compression refrigeration working mixture of halogenrsubstitutedhydrocarbon refrigerant and mineral oil lubricant a copper platinginhibiting amount of a group IV-B .organo-m'etallic compound.

'C'ompounds which have been found to'be eifective copper platinginhibitors and which are used in this-invention are compounds having thestructural formula:

R1 'R, Rl Ra where M is tin, lead or germanium, R R R and R arehydrocarbon radicals, hydrocarbonoxy radicals or carboxylic acidradicals and R is a hydrocarbondioxy radical or a dicarboxylic acidradical.

It is preferred to use organo-tin compounds in the practice of thisinvention since organortin compounds are generally better copperplatinginhibitors .than organogermanium and organo-lead compounds.However, organo-germanium and organo-lead compounds-arealso effectivecopper plating inhibitors ,andl-can be used in the practice of thepresent invention. p

The group IV-B organo-metall-ic copper plating inhibitors used in theinvention preferably have at leastone substituent which is ahydrocarbonoxy -radical, a hydrocarbondioxy radical, a .carboxylioacidradical or a dicarboxylic acid radical. "It has been found that thesecompounds are somewhat more effective in suppressing copper plating thanaregroup -lV-B organo-metallic compounds'having-all hydrocarbonsubstituents although these to thead'ditiyes of this invention, andaccordingly the additives preferably contain at least one hydrocarbonradical substituent.

The hydrocarbon substituent radicals on the copper platinginhi-bitors ofthe invention are normal, branched chain-or cyclic hydrocarbonradicals.Aliphatic, alicyclic -or aromatic'radicals are suitable. It is preferredthat the S' aliphatic and a'licyclic substituent radicals are saturatedalthough inhibitors with unsaturated aliphatic and ali- -cyclicsubstituent radicals can be used. Preferred hydrocarbon radicals arethose having about 1 to'20 carbon atoms per radical. "Examples ofspecific hydrocarbon radicals which :are suitable substituents on thecopper plating inhibitorsof this invention are methyl, ethyl,

propyl, bntyl, :amyl, :cyclohexyl, dodecyl, l-butenyl,

.atom of the organo-metallic compound. Preferred molec ular size of thehydrocarbonoxy radical substituents is about 1 to 20 carbon atoms.:Specific examples of suitable substituent hydrocarbonoxy radicals aremethoxy, ethoxy, propoxy, .isopropoxy, .butoxy, cyclopentoxy,cyclohexoxy, benzyloxy, phenoxy, toloxyandthe like.

The carboxylic acid substituents on the copper plating inhibitors of theinvention are any of the above described hydrocarbonradicals-connectedby to'jthe'metal atom of the inhibitor.Preferred-molecular size of the carboxylic acid substituents is about2-21 carbon atoms. Specific examples of suitable carboxylic acidsubstituent radicals are acetic, .propionic, butyric, lauric, stearic,naphthenic, benzoic,hexahydrobenzoic, isobutyric, isovaleric,3-butenoic, :senecioic acid radicals and the like.

The copper plating inhibitors-used in the invention can be dicarboxylicacid substituted compounds or hydrocarbondioxy substituted compounds.The dicarboxylic acid or'hydrocarbondioxy substituent radicals areillustrated by R in the above'structural formula. 'The-dicarboxylic acidsubstituent comprises a hydrocarbon connected by groups to the metalatom of the organo-metallic compound. The hydrocarbondioxy substituentcomprises .a

hydrocarbon connected by two oxygen atoms to the metal atom of theorgano-metallic compound. The hydrocan V v bon portion of thehydrocarbondioxy and dicarboxylic acid substituents can be aromatic orit can bexsaturated .or unsaturated aliphatic .oralicyclic. It ispreferredthat the hydrocarbon portion of the dicarboxylic acid andhydrocarbondioxy substituents have a molecular size of about 2 to 10carbon atoms. Specific examples of suitable hydrocarbondioxy substituentradicals are ethylene- -dioxy, 1,2-propylenedioxy, 1,3-propylenedioxy,1,2-butylenedioxy, 1,3-butylenedioxy, 1,4-butylenedioxy, 1,4-dioxy,Zlmtene. Q y ene, L -cy o e y nedioxy nu ca'ls and the like. Specificexamples of suitable-dicar- 'boxylic acid radicals are maleic,LZ-benZenedicarbQXYJic, malonic, 1,2-cyclohexandicarboxylic, .phthalic.acid radi-' cals and .the like.

lead and the like. The use of di-n-butyltin diacetate, din-butyltindilaurate, di-n-butyltin maleate, di-n-butoxy tin, di-n-butylethylenedioxy tin, di-n-butyltin phthalate and 1,4-dioxy 2-butene tin isespecially preferred.

The halogen-substituted hydrocarbon refrigerants which form a part ofthe improved working fluids of this invention can be any of thehalogen-substituted hydrocarbons conventionally used as refrigerants incompression refrigeration systems. Examples of these refrigerants aredichlorodifluoromethane, 1,2-dichloro-1, 1,2,2-tetrafluor'oethane,dichloromonofluoromethane, monochlorodifluoromethane,trichloromonofluoromethane, 1,1,2-trichloro-1, 2,2-trifluoroethane andthe like.

The mineral oil lubricant which forms part of the novel working fluid ofthe invention can be any conventional compression refrigeration mineraloil lubricant. Such oils generally have viscosities in the range of 75to 500 SUS 100 F., pour points of F. to 50 F., low fioc points and donot vaporize at conditions in the refrigeration system.

It is necessary according to the present invention to incorporatesufiicient of the organo-metallic compound in the lubricant-refrigerantmixture to inhibit copper plating in the refrigeration system. Generallythe use of amounts of the organo-metallic copper plating inhibitor inthe range of 0.01% to 2% by weight of the lubricant is sufiicient toeffectively suppress copper plating. However, amounts outside this rangecan, on occasion, be successfully used.

The following illustrates a practice of the present invention:

Di-n-butyltin maleate is added to a compression refrigeration workingfluid comprising dichlorodifluoromethane refrigerant and mineral oillubricant. The din-butyltin maleate is used in amount of 0.5% of thelubricant. This resulting mixture when used as working fluid in acompression refrigeration system, effectively suppresses copper platingin the system.

Example The effectiveness of refrigerator working fluid additives ofthis invention as copper plating inhibitors was tested in the followingway. Minor amounts of the inhibitors were added to different portions ofa mixture comprising about 50% of carbon tetrachloride and 50% of anaphthenic-base distillate refrigerator lubricating oil. The oil hadbeen furfural-refined, acid treated, and clay treated; the oil had anAPI gravity of about 24.4 and a S.U. viscosity at 100 F. of about 160seconds. A coppersteel coupling was suspended in each mixture, and eachmixture was maintained for extended periods of time at 150 F. At the endof the test period, the steel surface was examined to determine thepercent of the steel surface on which copper had been deposited. Thefollowing table shows the results obtained with inhibitors of thisinvention as compared to a control sample having no inhibitor:

Inhibitor mt., Test Percent of Sample Inhibitor Wt. Period, SurfacePercent Hours Plated Oil 72 80 di-n-hutyltln dilaurate.- 0. 5 220 0 -rl00.5 288 100 di-n-butyltin dlacetate. 0. 4 504 slight stain di-n-butyltinma1eate. 0. 45 1, 000 0 4 ingessentially of a halogen-substitutedhydrocarbon refrigerant, a lubricating amount of a mineral oil lubricantand a copper-plating inhibiting amount of an organo-tin compound havinga structural formula selected from the group consisting of:

and

Sn=Rs where: R is a 1 to 20 carbon atom hydrocarbon radical selectedfrom the group consisting of: alkyl, cycloalkyl, alkaryl and arylradicals; R is a radical selected from the group consisting of -OR and ol R. wherein R is as defined above; R and R are radicals each selectedfrom the group consisting of R OR; and

wherein R is as defined above; and R is a radical having 2 to 10 carbonatoms and is selected from the group consisting of hydrocarbondioxy anddicarboxylic acid radicals wherein the hydrocarbon portion is selectedfrom the group consisting of aliphatic, alicyclic and aromatic portions.

2. A composition according to claim 1 wherein R is a hydrocarbonoxyradical.

3. A composition according to claim 1 wherein R is a carboxylic acidradical.

4. Composition according to claim 1 wherein said organo-tin compound ispresent in an amount equal to between 0.01 and 2.0 wt. percent of themineral oil lubricant present in said compression refrigeration workingfluid.

5. A compression refrigeration working fluid consisting essentially of ahalogen-substituted hydrocarbon refrigerant, a lubricating amount of amineral oil lubricant and a copper-plating inhibiting amount of anorgano-tin compound selected from the group consisting of dim-butyltin'diacetate; di-n-butyltin dilaurate; di-n-butyltin maleate;

di-n-butyl dibutoxy tin; di-n-butyl ethylenedioxy tin; di-

n-butyltin phthalate; and 1,4-dioxy 2-hutene tin.

References Cited in the file of this patent UNITED STATES PATENTS1,966,881 Braunn July 17, 1934 2,060,728 Fleischer Nov. 10, 19362,288,288 Lincoln June 30, 1942 2,421,631 Lincoln June 3, 1947 2,468,544Clark Apr. 26, 1949 2,493,213 Altamura J an. 3, 1950 2,523,863 CookSept. 26, 1950 2,578,359 Jenkins Dec. 11, 1951 2,789,105 Tamka et a1.Apr. 16, 1957 FOREIGN PATENTS 702,848 Great Britain Ian. 27, 1954

1. A COMPRESSION REFRIGERATION WORKING FLUID CONSISTING ESSENTIALLY OF A HALOGEN-SUBSTITUTED HYDROCARBON REFRIGERANT, A LUBRICATING AMOUNT OF A MINERAL OIL LUBRICANT AND A COPPER-PLATING INHIBITING AMOUNT OF AN ORGANIC-TIN COMPOUND HAVING A STRUCTURAL FORMULA SELECTED FROM THE GROUP CONSISTING OF: 